Date: Tue, 4 Dec 2007 18:57:44 +0000
From: Christoph Hellwig <hch@infradead.org>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
       Roland McGrath <roland@redhat.com>, David Smith <dsmith@redhat.com>
Subject: Re: [patch 2/2] Linux Kernel Markers - Create modpost file
Message-ID: <20071204185744.GB21568@infradead.org>
References: <20071204181845.895090222@polymtl.ca> <20071204182403.319351701@polymtl.ca>
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On Tue, Dec 04, 2007 at 01:18:47PM -0500, Mathieu Desnoyers wrote:
> This adds some new magic in the MODPOST phase for CONFIG_MARKERS.
> Analogous to the Module.symvers file, the build will now write a
> Module.markers file when CONFIG_MARKERS=y is set.  This file lists
> the name, defining module, and format string of each marker,
> separated by \t characters.  This simple text file can be used by
> offline build procedures for instrumentation code, analogous to
> how System.map and Module.symvers can be useful to have for
> kernels other than the one you are running right now.
> 
> The strings are made easy to extract by having the __trace_mark macro
> define the name and format together in a single array called __mstrtab_*
> in the __markers_strings section.  This is straightforward and reliable
> as long as the marker structs are always defined by this macro.  It is
> an unreasonable amount of hairy work to extract the string pointers from
> the __markers section structs, which entails handling a relocation type
> for every machine under the sun.

Generating something like this might make sense.  But until you actually
add ome example code, e.g. to generate a tracing module for each probe
marker in a given module I don't see any point in adding this.

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